Tag Archives: Bonefishing Mangrove Flats

MANGROVE DIE-BACK IN THE ABACO MARLS: THE FACTS

For some time now, there has been understandable concern about the increasing evidence of mangrove die-back in the Abaco Marls and elsewhere in Abaco waters. Scientific investigations are ongoing and you will find some of the survey results so far on the excellent Abaco Scientist interactive mapHERE. You’ll find other relevant and authoritative mangrove material if you check out theBLOGmenu of the website.

The ‘200 sq. miles’ in my map is debatable, depending what one includes. Other estimates are of 300 or even 400 sq. miles. Whichever, the Marls cover a massive area of mangroves, islets, flats, channels and wonderfully diverse wildlife. A large proportion of the many species – fish, birds, turtles etc – depend on the complex ecology of the mangroves for food, shelter and breeding. Depletion of the mangroves from whatever cause will have a direct effect on the creatures of the Marls.

Ryann Rossi, a PhD student with North Carolina State University, has been researching the worrying phenomenon of mangrove die-back in the Marls this summer. She has written an interesting and informative account (conveniently in the RH ‘Facts about…’ style) that was published in Abaco Scientist last week. The blue links will take you to the ABSCI site for further information on each topic. I’m grateful to Ryann and ABSCI for permission to use the material.

Five Things to Know About the Mangrove Die-back in The Marls (at this point, anyway)

1. This die-back appears to be the result of multiple stressors acting together. Think of it in the sense of our own body – when our immune system is down, we are often more susceptible to getting sick. The same thing is likely happening to the mangroves.

2. It appears as though a fungal disease may be taking advantage of already stressed mangroves and causing die-back. We did preliminary surveys across Abaco and found fungal lesionsnearly everywhere. However, the fungus was present in different densities in different areas. In the die-back area nearly all the leaves remaining on trees have lesions. We think that this pathogen capitalized on the mangroves being weakened by other stressors such as hurricanes, which cause extensive leaf drop, change in the movement of water, change in sedimentation and erosion.

3. We are still working on identifying the pathogen associated with the lesions we’ve found. We are confident that it is a fungus and are currently growing fungal cultures in the lab to examine defining morphological characteristics in addition to using DNA sequencing to identify the culprit.

4. We have documented the presence of the Robust Bush Cricket (Tafalisca eleuthera) in the die-back areas as well as other areas with high densities of lesions. These crickets are documented to consume Red and White mangrove leaves. As such, we were concerned about their potential role in die-back. We set out a caging experiment to exclude the crickets from certain dwarf Red mangrove trees to see just how much grazing they may be doing in the die-back area. This experiment is ongoing.

5. The take home: there is likely more than one causal agent of the die-back in The Marls. Many factors govern mangrove productivity and functioning: nutrient availability, salinity, sedimentation rate, herbivory, and disease are just a few of the factors that contribute to overall mangrove function making it very difficult to pin point which factors may be driving the die-off. On the bright side, we are confident that we have a lead on the causes and we are working hard in the field and laboratory to fully understand what is going on in The Marls.

Mangrove Die Off on Abaco by Ryann Rossi, NCSU

This summer Stephanie Archer and I continued research efforts focused on determining the cause of the mangrove die-off in The Marls (work funded by the National Science Foundation). Our efforts were predominantly focused on the fungal pathogen we found associated with the die-off site. We created a small citizen science and outreach project to document the presence or absence of the pathogen across Abaco. This project consisted of short surveys and leaf collections. In total, 92 areas were surveyed including locations from Abaco and San Salvador. We also took this outreach project to the annual Bahamas Reef Environment Education Foundation (BREEF) teacher training conference. There we disseminated survey packets to teachers from islands throughout The Bahamas who will help us collect more data on the presence (or absence) of this pathogen on other Islands.

Three men on a skiff – Abaco Marls

On Abaco, we constructed an experiment to investigate the role of grazing and the presence of fungal lesions on Red mangroves. We simulated grazing using crafting scissors to cut small sections on 600 leaves in 4 different mangrove creeks. We observed the leaves for 28 days to determine if cutting leaves predisposed leaves to fungal infection. At these sites we also trapped for insects to gain an idea of what kind of grazers may be chewing on the leaves. We also did a series of disease incidence surveys that will be routinely monitored for disease progress over the next 2 years. These surveys will allow us to systematically track the progress of the disease. In addition to our field work, we spent many hours in the laboratory isolating fungi from leaves to grow in culture. These cultures were brought back to North Carolina State University and will be sequenced in order to help us identify the fungal pathogen responsible for making the lesions on the mangrove leaves.

A BONEFISHING CHALLENGE ON ABACO

In January I posted an article called BONEFISHING ON ABACO: A CHALLENGE IS ACCEPTED. This stemmed from contact online with fisherman and fly tyer Mark Minshull, who kindly tied some flies for me to try on the Marls. In the post I showed pictures of my manky flybox and his immaculate flies. We agreed to see how things turned out while I was on Abaco in March, and that I would report back…

Mark 1 Specimen Bonefish Flies

THE ‘WHICH?’ REPORT ON MARK 1 BONEFISHING FLIES

We set out to test the efficacy of prototype ‘Mark 1’ bonefishing flies in the waters of the Abaco Marls. Our testers came from the US (TC & AH), Northern Ireland (AB), and England (RH). All are proficient fly fishermen with experience of several prime bonefishing destinations between them, except for the Englishman RH who was included to add balance to the trials by adding the element of incompetence. His fly box remained an object of ridicule throughout the tests, until he resorted to using a more carefully chosen small fly box containing his most successful flies, some ‘Delphi Club Approved’ flies and the test flies.

QUALITY All our testers agreed that the Mark 1 flies were beautifully designed and tied. As flies, their quality was rated ‘superb’; ‘bloody good’; and ‘very impressive’. As potential winners for the waters of Abaco, however, there was considerable doubt about the suitability of the pattern for colouring, shape and size.

THE TEST AREA We used the huge area of prime bonefishing territory of the mangrove swamps and sand banks on the west side of Abaco known as the Marls. Our testers were familiar with the waters and all had fished them numerous times. The sea depth, depending on tide, is a few feet at most. The consistency of the bottom is of lightweight, pale coloured mud.

It is usually easier to look out for the shadows of the fish on the light bottom than for the fish themselves, which are often difficult to see in the water. Half-close your eyes and look at this image – the fish almost disappears, but the shadow is clearly visible. It is hard to believe the wonderful colouring of the fish until it is out of the water.

THE TESTS The initial reservations of the testers unfortunately proved justified in the field. The testers all found that the fish tended not to follow the flies at all, and mostly behaved as if they had not seen them, even with the most accurate casts. The few ‘follows’ observed produced refusals of the fly at the end. Disappointingly, no fly was taken by a single fish throughout the trials.

OBSERVATIONS Our testers had some useful comments. Above all, the Mark 1 flies were undoubtedly of excellent quality and design. They simply were not suited to the waters – or the bonefish – of Abaco. TC thought they might work in Belize. It was thought that larger versions might attract permit. Overall, the Mark 1s were so radically different from the tried and tested fly patterns used successfully on Abaco that the 3 competent fishermen soon forsook the experiment and caught fish using more familiar flies. The 4th tester, lacking any finesse, might have fluked a take against the odds , but even he drew a blank.

THE PROFESSIONALS The Guides in each case had been fishing the Marls since they could walk and hold a rod. They each examined the flies, shook their heads and kept their thoughts to themselves. We interpret this as indicating a tendency for the local guides to doubt the effectiveness of the Mark 1 flies.

CONCLUSION The flies that catch the bones on Abaco tend to be pale and to have ‘streamer’ tails and / or a fair amount of sparkle. A touch of pink seems to be good. Too much pink, not so. Rubbery legs can be very effective (except in the fisherman after lunch). But lovely lifelike dark shrimp imitations are of no interest to the fish of the Marls.

‘WHICH?’ RATINGS FOR THE MARK 1 FLY

Design and construction *****

Ease of use *****

Effectiveness for Abaco waters *

All photos RH. Thanks to Mark for creating the challenge and for being a great sport

BONEFISHING ON ABACO: A CHALLENGE IS ACCEPTED

Here is my fly box. It is a qualified success, as is my fishing. The fly box is rather better organised than I am, though. Some of the flies in it are routinely ignored by others to whom I helpfully offer the box. I’ve found the best plan is to stick with the silvery shrimpy patterns, especially the ones with pink heads. Then nobody gets upset. And from time to time I get lucky (see header image).

Recently, a proper fisherman started to follow my blog, and I his. I immediately recognised one of the fishing lakes on his site, one where I have fished in the past. One thing led to another and I seem to have agreed to trial some of Mark’s expertly tied flies on the Abaco flats in March…

Mark’s Bonefish Patterns

I am very keen on the principles of ‘Catch and Release’. So keen that I have developed my own specialist methods (designed for fishing with barbless hooks) using what might be termed ‘Early C&R’. These may include some or all of the following on any given day:

‘THE PHANTOM CATCH’ As the fish follows the fly, and the instant before it commits to a lunge for it, abruptly whisk the fly away from under its nose with a sharp reflex ‘trout-strike’. This will ensure that both the fish and your fly remain untroubled by actual contact. This is the most advanced form of Early C&R.

‘THE BIG MISSED TAKE’ As the fish takes your fly firmly in its mouth, become preoccupied by the fact that your left foot is planted firmly on a horrid tangle of line around your feet. You will feel the solid take, but instantly realise that your retrieve is hopelessly compromised. With some relief, you feel the line go slack as the fish shakes itself free…

‘THE REEL THING’ Hook the fish. Feel the weight on the end of the line. It’s heavy. Nice one! Turn in muted triumph to your boat partner to shout excitedly “Got One”. As you do so, allow the line somehow to snag round the rod handle and the reel simultaneously. Before you have even begun to figure how to sort this out, the fish will have released itself and be heading for the horizon.

‘THE STICKY SITUATION’ Hook the fish. Reel in confidently, keeping the line taut and the fish under your masterful control. Allow it to run if it wishes. Proceed with the same efficiency until you notice a single mangrove stem sticking out of the water 30 feet away. Using your skill, ensure that the fish suddenly has the chance to move to the other side of the stick, winding the leader or line (either will do) round it. Prepare for the ‘twang’ when the inevitable break occurs. Your fish is away.

‘THE MANGROVE SWAMP’ Hook a fish. Play it competently until the moment your boat partner or guide gives you some word of encouragement or (worse) praise. Immediately, permit the fish to make a fast break for the nearest clump of mangroves even if it is over 100 feet away. The consequent entanglement round the myriad stems will be sure to lose you the fish and your fly. NOTE: all third party encouragement will diminish after this form of EC&R. Praise will not be repeated.

Mark has just made a challenge public on his website in a post called All aboard for Abaco!“This little packet of flies is destined for the Bahamas… What stories will they conjure up in time? Rolling Harbour, Abaco… All will be revealed in time! Thanks in advance to RH – I will keep everyone posted in due course! Looking forward to some beautiful pictures of Bonefish…”The flies in question are shown below. It is expected that they will prove to be effective. The expectation is Mark’s. My own feeling is more one of hope. I hope he knows what he is doing. I hope I know what I am doing.*

*The plan is to ask my boat-partner and guide – anyone with access to a rod, really – to “have a go with one of these little guys”. They are far less likely to be as skilled as I am at Early C&R, and are therefore far more likely to boat a fish. Job done…

NEST PROTECTION: WILSON’S PLOVERS ON ABACO (2)

This is the second of three vaguely planned posts about these delightful shore birds. They aren’t rare but they are approachable and fun to watch. During the nesting and hatching season, there may even be some gorgeous chicks on a beach near you (a phrase I never thought I’d find myself using). PART ONE identified the typical male and female adults found on the Delphi beach almost any day.

This post is about nest protection. Not the ingenious methods of the birds themselves, that will come next time. This is a story of protection by humans. The photograph above shows Nettie’s Point, one of the launching points for bonefishing skiffs being taken out to the Marls, a vast area of sea, low sand banks and mangroves where the fish are found. You hope. The skiffs gain access to open sea via an artificial channel carved out of rock. The early morning trip along it is one of the most exciting part of a fisherman’s day, as he or she sets out with a clean score sheet, a rod and a box of flies. And a cooler box with some food and maybe a Kalik beer or three.

This June, a pair of plovers decided to locate their nesting ‘scrape’ right in the middle of the cleared area where the trucks normally turn. This was by no means a wise home-planning decision, and they might well have found themselves being promptly relocated. Or (worst case scenario) ending up under a large Toyota. But not a bit of it. Instead, these small birds were looked after by the guides like this:

A makeshift castle was built all round the nest to protect it from any inadvertent truck-related tragedies. Meanwhile the male plover stood guard outside the castle, amiably watching the human activities.

I kept my distance but in fact he was quite unperturbed, perhaps sensing that we were not a threat. He still kept a beady eye on the proceedings, though.

Meanwhile, what of the wooden enclosure itself? At first glance, there didn’t look much to report. However, if you look in the centre of the picture, you’ll see the female peeping out from the nest.

I very slowly moved nearer, prepared to stop if the male became agitated, or if the female shifted her position. Both seemed quite relaxed, so I took a couple of shots and walked away to leave the birds in peace. Then I went fishing.

As a postscript, Nettie’s Point is the location of a remarkable geographical phenomenon, possibly the result of the cutting of the channel. Along one part of the cut, for about 30 feet, the water level sinks alarming in the middle, while remaining normal at each side. Then it levels out again. This remarkable mid-stream aquatic depression is quite disconcerting to motor through on a skiff, though eventually one gets used to it. (Note: not every fact in this post is 100% true. If you have some salt handy, take a pinch)

IT’S ALL WHITE – IT’S A REDDISH EGRET ON ABACO

Contrary to appearances from the header image and the one below, Reddish Egrets (Egretta rufescens) do not yet use cellphones to communicate. Nevertheless, the trick of having a good ear-scratch while standing in water on one leg is a good posey accomplishment.

All these photos were taken while we were bonefishing from a skiff far out on the Marls in the mangroves. Ishi poled us closer so that boat-partner Tom – a real photographer – could get some shots. Meanwhile, I did my best with my little camera that I take out on the boat – the one that won’t matter too much when it slips from my hand or pocket into the drink. These things happen: I lost a good pair of Costas that a gust of wind unkindly whisked away when I took them off to change a fly.

This egret comes in two very different ‘colourways’. The classic version has a slatey-blue body and a reddish head and plumes. The white morph is pure white. The only similarities between the two are the two-tone bills with the black tip; and the blue-grey legs and feet.

True Reddish Egret, as you might expect it to look

The white morph

I’m not certain of the proportions of each type on Abaco, but I have certainly seen twice as many white ones as true reddish ones. There seem to be quite a few around – there are plenty of fish for them and dozens of square miles of human-free space in which to stalk them. However as with many (most?) of the bird species, there is a declining population for all the usual man-related reasons, and these fine birds have now had to be put on the IUCN ‘near-threatened’ list.

The bird kept an eye on us as we drifted closer, but was unperturbed. It continued to poke around in the mud, and occasionally it moved delicately but quite quickly to a different patch.

We watched the bird for about 10 minutes. Then we returned to what we were really there for – Tom to catch bones with practised skill, and me to wave the rod incompetently around until some passing fish took pity on me and grabbed my fly, knowing it would soon be released once all the fuss was over…

WILLET OR WON’T IT… GET CLOSE TO YOU?

Willets (Tringa semipalmata) are large sandpipers, familiar as shore birds, foragers on sand bars and mudflats, or out in the mangrove swamps. Some might describe them as quite solid and plain to look at. Until they take flight, when their gorgeous wing patterns are revealed.

Willets are ground-nesting birds, often breeding in colonies. They use their stout bills to forage on mudflats or in shallow water for insects, crustaceans, marine worms and occasionally plant-life. They tend to keep their distance, and in the past I have only managed this sort of unimpressive snapshot, not least because I normally only take a small basic camera out on the water in case it – or I – should fall in.

However, we recently fished from the prow of a skiff parked on a sandy spit on the Abaco Marls, as bonefish came past on the tide. It was a productive hour for my boat-partner, though frankly less so for his boat-partner… As we fished, and to our surprise, a willet landed of the point of the spit to feed, and gradually worked its way towards us seemingly unconcerned by the skiff, by us or by the fish action. It started off about 30 feet away, and at close quarters it was far less drab and notably more elegant than expected.

It foraged slowly towards us, keeping a beady inky-black eye on us

At one time it came within a very few feet of us, then decided it had come close enough. We watched it stepping delicately away on its semi-palmated feet. The shot isn’t clear enough to show the slight webbing between the toes. However, you can clearly see the barred tail.

In the c19 and early c20 there was a sharp population decline of these fine birds due to hunting. I’m not sure if it was for feathers, food or fun. All three, probably. Their population has recovered and their IUCN status is currently ‘Least Concern’, but like so many similar species they remain at risk, especially through continued habitat loss.

The Willet call and song are very distinctive, and are reproduced here via the great bird-noise resource Xeno-Canto

BABY BONEFISH, CASUARINA, ABACO: HIDING IN PLAIN SIGHT…

Bonefish are difficult to see in the water at the best of times. Shining silver out of water, but pale grey shadows underwater. Fishing under cloud cover and / or (especially ‘and’) when there’s a ripple on the water can be atritional. Sight-casting becomes impossible, and the best recourse is to locate the cloudy patches of water that show where the fish are feeding on the bottom. Chucking the fly into – or beyond – one of these and stripping back may be the only way to get a fish in such adverse conditions. What’s needed is clear sky, sunlight, good polaroids, patience, and keen eyes to scan the water for dark shadows moving across the sand… Or, in my case, simply waiting for the guide to hiss “Hey! Rolling Harbour. Three fish, 40 feet, 10 o’clock moving right, see them? Go now!”. By then, there’s a 50 / 50 chance I may have located them and got my act together enough to (try to) cast at them…

This picture of an adult fish, just caught on the Marls and released at once, shows how a bonefish can easily blend in with its underwater surroundings… but it can’t hide the dark shadow it casts.

Two days later we went to Casuarina with friends who wanted a day’s wading on the extensive flats there. This photo shows a juvenile fish close to the beach there, on a glorious sunny day with a light breeze (the header picture [double-click] was taken the same day – low water over pale sand as far as the eye can see). I’d never have noticed this little fish, had I not seen the dark shadow it cast on the sand, magnified by the distorting effect of the ripples.

Without the distortion from surface ripples, the bonefish shape can be clearly seen. It’s hard to imagine that by the time this little fish has reached a weight of 2 lbs, he will be capable of stripping your line down to the backing in seconds… or could he?

No, not, in fact. This fish, with its deeply forked ‘bonefish’ tail, is in fact a YELLOWFIN MOJARRAalso known as shad. As Zach Zuckerman of the CAPE ELEUTHERA INSTITUTEwrites in kindly emphasising that the fish above is not a bonefish, “the yellowfin mojarra… is related to the mottled mojarra mentioned in Chris Haak’s text(see below). Yellowfin mojarra and bones share the same habitats, and mojarra also feed off of benthic invertebrates”. Which brings me to some interesting recent findings by the CAPE ELEUTHERA INSTITUTEin conjunction with the BONEFISH & TARPON TRUST. We saw a single small fish. It looked like a bonefish (though I guess the yellow fin markings suggested otherwise). It was in fact a similar-looking species. Where are all the young bones? The babies? How do they protect themselves from the many predators of juvenile fish?

“Since May 2011, Christopher Haak, a PhD student (and avid fisherman) at the University of Massachusetts, Amherst, along with other scientists, has been trying to solve the mystery of where juvenile bonefish live, from settlement through the time they join adult populations on the flats. Exhaustive efforts to locate juveniles along the densely-developed coastlines of Florida were met with little success, leading researchers to the comparatively pristine shorelines of The Bahamas to continue their search.

For the past one-and-a-half years, they have scoured the coastlines of South Eleuthera, conducting 1000+ seine hauls, encompassing a broad range of coastal habitats. This project is funded by Bonefish & Tarpon Trust and based out of CEI. These efforts (with the help of South-Eleutherans; thanks Denny and Kelsey Rankin!) have succeeded in locating over 800 juvenile bonefish as small as one inch in length, and have revealed some intriguing trends. For example, contrary to what might be expected, juvenile bonefish do not appear to frequent the mangrove creek systems or expansive tidal flats commonly used by adults, preferring instead to remain along shallow, sheltered shorelines near deeper basins or channels.”

Can you find the juvenile bonefish among the mojarra in the picture below?

“Perhaps the most remarkable finding to date is that nearly every bonefish collected was in the company of much greater numbers of like-sized mojarras (a common schooling baitfish known to Bahamians as shad). These juvenile bonefish exhibited markings and coloration not apparent in adult bonefish, but very similar to the mojarras with which they were caught. By blending in with considerably greater numbers of the model species, the mimics may be reducing their predation risk, and increasing their chances of survival. In the case of bonefish, this hypothesis would also explain why juveniles are so rarely observed; they are well hidden within schools of mojarras! From a conservation perspective, this suggests that bonefish populations may be dependent upon healthy mojarra populations, important information for resource managers.

This research is also producing valuable information about the diverse juvenile fish communities that inhabit Eleuthera’s shores. Myriad seine hauls of the island’s beaches, bays, sounds, and creeks have catalogued juvenile fishes from a wide array of species, including other flats inhabitants like permit, reef fish such as parrotfish, jacks, and wrasses, and some very unusual demersal critters such as shortnose batfish. The high densities and diversity of juvenile fishes revealed by this study serves to highlight the importance of these nearshore habitats to healthy adult fish populations of all kinds, underscoring the need to preserve and care for our coastlines.”

ADDENDUMWith thanks to Aaron Adams of theBONEFISH & TARPON TROUT for use permission, here is a great size indicator for baby bonefish, taken by him some years back in connection with a juvenile bonefish project.